In order to reduce the inhalation effort required to hold open the air inlet valve of a demand type diving regulator it is common practice to cause some of the air from the inlet valve to flow through the breathing chamber directly into the breathing port or mouthpiece tube. This air flow educts air from the breathing chamber whereby the pressure in the breathing chamber remains below ambient pressure. Since the inlet valve opens in response to such a reduced pressure in the breathing chamber, it remains open without any heavy inhalation by the user. In addition to this so-called venturi port, the air inlet also includes one or more additional ports which are remote from the venturi port and which supply air to the breathing chamber.